Here’s a question that I get commonly: “What do I do to an outdoor area that might have been contaminated by a dog with parvovirus?”

There’s not a lot of research to back anything up, but understanding the virus and some basic principles helps us come up with some reasonable recommendations.

Parvovirus is…

Highly tolerant of environmental exposure, disinfectants and other things that kill most viruses.

Shed in potentially massive amounts in the feces of sick animals, but also potentially by some healthy animals.

The cause of a potentially fatal disease.

A pathogen against which we have effective vaccines.

Really only a concern for unvaccinated (or inadequately vaccinated) dogs.

There’s definitely cause for concern if a puppy with parvo infection has passed diarrhea outside. We can assume there’s lots of virus there, and that the virus is going to be able to survive there for some time. We don’t know how long, and it will certainly vary with environmental conditions (e.g. temperature, pH of the soil, humidity, sunlight), but it’s safe to assume that it will be a fairly long time in most situations.

So, what do we do?

Disinfection of outdoor surfaces is pretty futile. Disinfectants don’t work well in the presence of organic debris (dirt), so pouring disinfectants on grass or gravel will not likely do much (except put a lot of disinfectant residue into the environment). Unless it’s happened on a surface like concrete or asphalt (both of which can still be hard to adequately disinfect because they are porous), leave the bleach bottle in the cupboard.

Removing feces is a good first step. This actually removes the vast majority of virus that has been passed. It might require using a shovel to get rid of some of the diarrhea-soaked grass or soil, but removing as much of the visible contamination as possible is key.

Restricting access to the area can’t hurt, when it’s feasible. That doesn’t mean cordoning it off and keeping everyone away. The focus should be to keep young, unvaccinated or incompletely vaccinated dogs (and dogs that have contact with those dogs) away from the area.

Raking the site can help turn over the substrate (e.g. dirt, soil, gravel) and get more exposure to UV light. Sunlight is our best outdoor disinfectant, and raking can help expose virus particles that are hidden away.

As always, prevention is better than cure. Preventing these situations is ideal, but admittedly not always possible. Things that can help include:

For the third time in the past year, Macon-Bill Animal Welfare in Georgia (USA) has a problem with canine parvovirus. The shelter is closed for two weeks in response to a puppy testing positive for this highly contagious virus that can cause serious disease in dogs (almost exclusively in unvaccinated puppies). At first glance, it may seem like an overly-aggressive response. A single parvo case isn’t too surprising in a shelter, and if appropriate routine precautions are followed, there are sound protocols to isolate parvo suspects and a good vaccination program, the risk to other animals can be contained.

In this outbreak, 14 puppies have been euthanized (though some reports differ). Again, the news reports are pretty crappy and it’s unclear whether all the puppies were sick or whether they were euthanized because they were exposed. The statement that parvovirus infection is "most times fatal for dogs" is wrong, since it’s usually treatable, but it certainly takes time, effort and money - things that may be of limited availability in a shelter. Also, if the shelter has inadequate facilities or personnel to properly treat and contain parvo, euthanasia gets considered more readily that in better equipped facilities.

The first report also says that the shelter refunded adoption fees of people who adopted puppies that subsequently died from parvo, so it does sound like there was probably a real (and possibly large) outbreak.

Closing a shelter is an extreme move but it’s sometimes required. It helps reduce the number of animals in the facility in order to make isolation of sick animals, separation of groups, management of exposed and infected animals and many other aspects of the infection control response easier. It also stops adding fuel to the fire, by halting admission of new susceptible animals that can get sick and thereby propagate the outbreak.

Some shelter outbreaks are the result of poor routine management (and some incompetence). Some are the result of inadequate response to an infectious animal. Some are an over-reaction to a limited and containable problem. Some will occur despite the best practices in the best facility. That’s the nature of infectious diseases. Any time there’s an outbreak, a shelter needs to figure out which of the above categories they fit in so that they can reduce the risk of future problems.

(For tracking of selected infectious diseases and outbreaks, stay tuned for the launch of WormsAndGermsMap. More information to come!)

In Canada (like most places), there's no semblance of a formal surveillance program for infectious diseases of companion animals. We're left with anecdotes and whatever short-term research projects we can put together to try to figure out what's happening in our companion animal populations. Not ideal, but better than nothing.

Over the past month or two, I've been hearing more rumblings about canine parvovirus infections in dogs in Ontario. Nothing too dramatic, just a spike in calls and emails about cases, mainly typical parvo cases (e.g. disease in young and un- or inadequately-vaccinated puppies, outbreaks in groups like shelters and breeding kennels) with some cases that seem more severe and some in dogs that seem to have appropriate vaccination history or in older dogs. It doesn't seem to be due to a focal outbreak, since these may be occurring in a few different regions in Ontario. This type of anecdotal information is far from definitive but enough to start asking questions.

So is something happening in Ontario? I'm still not sure. Sometimes situations like these are just because people are talking and we're hearing more about little clusters that go on all the time under the radar. However, this could be real and caused by a variety of factors such as decreasing vaccination rates, increased parvovirus circulation in some regions or a change in parvovirus strains.

The only way to truly figure out what's happening is to get more data. That's not an easy proposition since surveillance networks aren't established and there's no money to do any disease surveillance like this. However, Ontario veterinarians who are seeing parvo cases can feel free to provide more info and to send samples for typing.

An interesting and frankly somewhat scary report in an upcoming issue of Veterinary Microbiology(Clegg et al 2012) provides further information suggesting that cats might be a source of canine parvovirus infection. This potentially fatal infection, which typically affects young unvaccinated (or inadequately vaccinated) puppies, is a major problem, and outbreaks occur (not uncommonly) in some high-risk populations like shelters.

In the 1970s, a new form of canine parvovirus, CPV-2, emerged and rapidly spread worldwide. That predates my veterinary career but I've heard stories of clinics where you couldn't turn a corner without stepping on a dog that was hospitalized for treatment of parvo, since it was a new disease and vaccines were not yet available. CPV-2 was shown to be able to grow in cat cells in the lab, but not in live cats, so it was generally assumed that dogs had CPV and cats had their own closely related virus, feline panleukopenia virus (FPLV). However, new variants of CPV-2 have emerged over time, and these seem to have a greater ability to infect cat cells in the lab, and disease caused by these strains has been reported in cats both experimentally and in limited real-world situations. However, it was still considered an uncommon event and the role of cats in parvovirus infection of dogs was largely thought to be inconsequential.

Or maybe not.

In this new study, researchers collected fecal samples from 50 cats in a cat-only shelter, and 180 samples from 74 cats at a shelter than housed both dogs and cats. Canine parvovirus shedding was identified in 33% of cats from the cat shelter and 34% of samples from the dog/cat shelter. A concern with a study like this is cross-reaction of tests for CPV and FPLV, but they went a few steps further to confirm that the virus was indeed CPV, not its feline relative. They also showed they could grow the CPV from fecal samples in cells in the lab, which means they were detecting live virus in the animals, not just dead viral bits working their way through the cats' intestinal tracts.

The results are interesting and concerning, since they showed that a pretty large percentage of cats in some situations could be shedding live CPV, making them a potential source of infection for dogs (and possibly other cats).

What makes this even more concerning is the duration of shedding that they identified when they collected samples from the dog/cat shelter over time: cats shed the virus for up to 6 weeks, despite appearing healthy.

This raises concerns about the potential role of cats in the spread of CPV. Cats and dogs don't tend to mix much in parks or outside, but CPV is a very tough virus that can survive for a long period of time in the environment. It's certainly plausible that cats could be depositing CPV-laden feces in the outdoor environment, and since the virus can survive the outdoor exposure and some dogs are notorious poop-eaters, it's a route of transmission that can't be dismissed. Cross-contamination within shelters is also a concern.

The true role of cats in canine parvovirus infection isn't known and it's probably quite limited compared to dog-to-dog spread. However, this study shows that we at least need to be thinking about it and considering cats when dealing with parvovirus problems in shelters and households.

Some things to think about:

Young puppies should be kept away from cats, especially strays and cats from shelters, until they are properly vaccinated.

Parvo is one more reason to have good physical and procedural separation between cats and dogs in shelters.

If a parvo outbreak in underway in a facility, prevention of potential cross-contamination from cats is required.

If a cat has been in contact with a dog with parvo, it should probably be considered potentially infectious and kept away from susceptible dogs for at least a few weeks.

Canine parvovirus vaccination is highly effective in dogs. If a dog is properly vaccinated, the risk from cats (or other dogs for that matter) is minimal.

A parvovirus outbreak has been identified at the Occupy San Francisco camp, with at least three dogs affected by the highly contagious and potentially very serious viral disease. The San Francisco SPCA has visited the camp and their temporary clinic was attended by "dozens" of dog owners (indicating lots of dogs at the camp). This is a nice proactive step to help contain the parvo outbreak and hopefully reduce the risk of transmission of various other infectious diseases amongst the animals. Some people appreciated the help. Others (probably the subset that complains about everything) accused the SPCA of spreading bad publicity to help shut down the camp. (I guess they'd rather have good press than healthy dogs.)

In many ways, it's not too surprising. "Occupy" camps are just asking for infectious disease outbreaks, more so in people, but the same risk factors are there for dogs. Whenever you mix together lots of different individuals from different sources, put them in close and prolonged contact and have hygiene challenges, you set the scene for infectious diseases. From a canine parvovirus aspect, heavy fecal contamination from dogs defecating in a small, concentrated area and unvaccinated dogs feed the fire even more. (I don't know for sure that the affected dogs were un- or incompletely-vaccinated, however given the excellent effectiveness of parvovirus vaccines, it's highly likely that sick dogs were not adequately vaccinated.)

Parvo isn't the only infectious disease problem at the camp. Kennel cough (now known as canine infectious respiratory disease complex, CIRDC) has also been identified. This syndrome, caused by a mix of bacteria, viruses and Mycoplasma, has greater potential to spread widely because some of these bugs are highly contagious and vaccination coverage in the population will be lower than for parvo. A large-scale kennel cough outbreak is quite likely if there is kennel cough activity at the camp.

What can you do to reduce the risk, whether it's while "occupying" or during your daily activities?

Have your puppy vaccinated as per your veterinarian's recommendations.

Don't take unvaccinated puppies to areas where there will be lots of other dogs. "Unvaccinated" includes puppies who have not had their full initial series of vaccines.

If your dog is sick, don't take it out in the public, especially to places where other dogs will be present.

If your dog gets sick during a public event, take it away promptly to reduce the risk of it infecting other dogs.

Don't let healthy skepticism grow to paranoia, and don't let political squabbles interfere with proper healthcare... both human and veterinary.

Disinfectants aren't very important for your average pet owner. They are more of an issue for kennels and veterinary hospitals, but there are situations where disinfection of an area contaminated by a pet might be needed.This is particularly true for certain microorganisms that can persist in the environment for a long time. The "poster bug" for this in dogs is canine parvovirus.

As many pet owners know, canine parvovirus is a very hardy virus. It can live in the environment for years and is resistant to many commonly used disinfectants. Careful cleaning and disinfection may be required in some situations where an infected animal has been in an area, particularly if it has passed diarrhea. Choosing an appropriate disinfectant can be a problem.

Bleach is a good disinfectant and can kill parvovirus, but it's noxious and isn't a good option for many surfaces. At our hospital, we use accelerated hydrogen peroxide, an excellent disinfectant that can kill parvovirus, but it's more expensive. Many other disinfectants are out there, and many have claims on their labels that they can kill parvovirus. Unfortunately, many (or most) cannot. Some just have claims that aren't based on any evidence. Others provide somewhat misleading information that can confuse buyers.

A good example is a product I was asked about today. It was a quaternary ammonium disinfectant, a common class of disinfectants with variable and often poor killing effect on parvovirus. The product claimed to kill parvovirus, but on closer reading, there's a major issue. The disinfectant is supposed to be used at a dilution of 4.5 ounces per gallon of water, yet the parvovirus-killing claim was for a dilution of 18 ounces per gallon. So, it might really kill parvovirus, but if it only does so at 4 times the typical concentration, how useful is it?

Do people that are using it under the pretense that it kills parvo realize the issue?Probably not.

Would people actually use it at 4 times the regular concentration?Perhaps. But that makes it 4 times as expensive, at which point it might actually be cheaper to use a better disinfectant like accelerated peroxide.

Is this fair advertising?That's questionable. Yes, all the information is there, but you shouldn't have to read the fine print. If the product says it kills parvo, it should be proven to do so at the regular recommended concentration. If it only kills parvo at high concentrations, that should be written right alongside the statement that it kills parvo.

The internet can be a strange place at times. You can find great, reputable and unbiased information right next to complete garbage. Often, the garbage is pretty apparent, but sometimes it's dressed up well or mixed in with some good information. That's a problem with veterinary advice and information sites.

Among the creative myths identified in a couple of minutes of searching:

- Metronidazole is a proven treatment for parvovirus: No. Metronidazole is an antibiotic that doesn't have any effect on viruses. Antibiotics are sometimes used in the treatment of parvovirus, but they are drugs that are used to prevent or treat problems caused by bacteria from the gut entering the bloodstream as a result of the intestinal tract disease. Metronidazole won't do that.

- MRSA is a virus: You can't make much more of a basic mistake than confusing a virus and a bacterium. Anyone who says this when purportedly writing medical advice is completely clueless.

There's no way to guarantee that a website is reputable or that the writers are knowledgeable, but here are some things I consider when scrutinizing information on the internet:

Who set up the website? Is it clear who's in charge?

Who wrote the information? Is it someone with actual credentials? For veterinary medical advice, is it a veterinarian? If it's a veterinarian, is it a specialist? If it's not a veterinarian, what expertise does the person have? Some people without veterinary degrees have expertise in some fields, but try to determine whether they truly have the qualifications to give advice on a particular topic. That's harder to do these days given the proliferation of mail-order "PhD" degrees, something that's not uncommonly encountered in unqualified people making poor veterinary recommendations.

Why is the website there? Is it an educational site or is it there to make money? Commercial sites aren't necessarily bad but you have to consider any conflicts of interest or ulterior motives. If there is an article about something, and the last sentence tries to sell you a product to fix that problem, be careful.

Does the information make sense and is it consistent with other websites? You can probably find a site somewhere to support any notion that you have, but does it really make sense?

Is the site relevant to your geographical area? This is particularly important for infectious diseases since they can vary greatly between regions. A disease may be a big problem in one area, and a website might provide excellent advice... but only for that area. It may be completely irrelevant or inappropriate for other regions.

Can they spell? The odd typo probably isn't a major issue (I do it myself). However, rampant and blatant abuse of the English language and an inability to spell important words properly should be red flag.

Searching the internet for pet health information is certainly not a bad thing to do. But, you have to critically assess what you read and remember that it's not always right. Use the internet as a resource but make sure that it's to supplement advice from your veterinarian, not to replace it.

A somewhat controversial study has just been published in the Journal of Veterinary Emergency and Critical Care (Savigny et al 2010). The study looked at the use of Tamiflu (oseltamivir) for the treatment of parvovirus infection in dogs. Tamiflu is best known as a potentially important influenza drug in humans. It's a neuraminidase inhibitor that can prevent replication of some viruses, such as influenza. It actually has no effect on parvovirus, but has been used by some veterinarians based on the hypothesis that it can have an effect on bacteria and perhaps prevent secondary bacterial infections, which contribute to the severity of parvoviral disease.

The study examined a relatively small number of dogs (35) with parvovirus infection. Some dogs received Tamiflu along with standard treatments, while the others received a placebo and standard treatments. There was no difference in major outcomes between the two groups, but control dogs lost more weight during treatment.

The study has some weaknesses and doesn't tell us too much, but it's the first objective investigation of this drug in dogs. There was no significant difference in relevant outcomes, but was that because the drug doesn't work, because the dose was too low (as has been suggested by some) or because the study was too small to detect a real difference? That's the big question.

Some veterinarians are completely convinced Tamiflu works for parvovirus infections and disregard any suggestion that it doesn't. Currently, there is no scientific evidence whatsoever supporting its use, and this study doesn't help much one way or the other. There are abundant anecdotes, and it's plausible that this drug could be useful for treating this disease, but there are a few concerns:

We really don't know whether it works. Continuing to use a treatment in the absence of objective information is not necessarily a good idea.

We don't know the appropriate dosage and duration of treatment for dogs. We also don't know which animals Tamiflu might or might not help. It is probably most effective (or perhaps only effective) early in disease.

Tamiflu is an important human influenza drug, and resistance is emerging in influenza. Can we justify using a drug that is a part of pandemic influenza control for the treatment of canine parvovirus, without any evidence that it is effective or needed?

The article's abstract concludes by saying "Based on these results, the true role of oseltamivir in the treatment of parvoviral enteritis remains speculative, although it is believed that further investigation is warranted." Very true.

We need two things:

Rational discussion about whether use of drugs like this is justifiable in animals.

Better studies to tell us whether it works, and if so, how to best use it.

If we end up using it, we also need surveillance to make sure routine use of this drug in animals doesn't contribute to resistance in humans. Unfortunately, the Tamiflu debate is too often full of anecdotes and arguments as opposed to logical discussion and sound evidence. Hopefully that won't get in the way of someone doing a more definitive study.

A couple of months back, Oprah adopted two cocker spaniel puppies from a shelter in Chicago. Unfortunately, within two weeks they both came down with parvovirus infection and had to be hospitalized. I'm sure both dogs received top-of-the-line care with no expense spared, but even so one of the puppies died. The other puppy came very close to dying as well, but happily she apparently has now recovered completely and is doing just fine (or quite likely better than fine, considering who her new owner is!).

Oprah also mentioned how one of her other dogs, Solomon, also suffered from a parvo infection years ago, but that dog was over a year old when he became ill. It's actually quite unusual for any dog to get parvo beyond one year of age - most adult dogs are not affected by the virus, unless perhaps their immune system is compromised for some reason.

These stories bring up a few interesting points to ponder:

It's great to adopt an animal from a shelter and give a homeless animal a home. It is an act of great kindness that I don't want to take anything away from in the least. However, it's important to realize that you never know what shelter dogs may be carrying, nor how well vaccinated they are.

Even if the animals are vaccinated once at the shelter, the protective effect may be less than ideal if a properly timed vaccination series is not completed.

In this case the pups may have been exposed to parvo after leaving the shelter, but they could have just as easily been exposed at the shelter, which begs the question of what else might they have been carrying? Bacterial pathogens such as Salmonella and Campylobacter are also particularly common in young dogs and cats (even healthy ones), and these are potentially zoonotic agents.

Young animals, particularly from shelters, arehigher risk in terms of the infectious diseases they can carry and transmit. That doesn't mean they shouldn't be adopted, but it does mean taking some extra precautions for the first several weeks they're in their new home. These include being very diligent about controlling stool contamination of any kind (which can be easier said than done during the house-training phase), preventing contact with high-risk individuals (e.g. young children, the elderly, anyone with a weakened immune system) and lots of handwashing on the part of everyone involved with the puppy (or kitten!).

Parvo is a very serious disease in puppies, yet people sometimes become a little complacent about vaccinating for parvo and other puppyhood diseases. Remember, though, that the reason parvo has become so much less common than it used to be is largely because of widespread and effective vaccination. I have to wonder about how well vaccinated Oprah's dog Solomon was to get the disease at the age he did, but there could easily be other factors involved as well. The virus is still out there, and if we become lax in our infection control practices - including decreasing exposure of puppies to the stool of other dogs, as well as vaccination - it's waiting in the wings for its opportunity to move in. Even with the very best care the infection can still be fatal.

It's also relevant to note that, as demonstrated by Solomon's case, just because parvo is very uncommon in adult dogs doesn't mean it's impossible for them to get it. It's important to always remain diligent.

Parvoviruses are quite species specific, so thankfully people cannot get parvovirus from dogs, but remember that puppies can get diarrhea from pathogens like Salmonella, which can be transmitted to people. There is also a human parvovirus which is the cause of Fifth disease. Just like the dog virus cannot infect people, the human virus cannot infect dogs.

Parvovirus can live for a very long time in the environment, however disinfecting an outdoor environment is not only impractical, it's impossible! We can disinfect clean, smooth surfaces like sealed ceramic floors and smooth countertops, but we can't disinfect outdoor environments with permeable, porous surfaces and abundant organic debris (dirt). Bleach is not active in the presence of organic debris, and porous surfaces allow bacteria and viruses to escape contact with disinfectants. So, while it's good to see that they are concerned about disease transmission, this particular aspect of their control efforts isn't going to be effective.

Parvovirus exposure is an ever-present risk in areas where multiple dogs congregate. The virus can be shed in the stool of even healthy-looking dogs. In this situation (like all others) the emphasis should be on keeping high-risk dogs (e.g. unvaccinated puppies) out of these areas, not closing the park altogether and attempting to disinfect it. Parvovirus vaccination is very effective, and properly vaccinated adult dogs are quite low risk. Prompt removal of stool by dog owners helps reduce the risk further by decreasing the risk of environmental contamination. Therefore, the three most important control measures are:

Ensure puppies are properly vaccinated.

Keep puppies out of areas visited by numerous dogs until they have been fully vaccinated.

Numerous outbreaks of Fifth Disease have been reported internationally. That, itself, is not particularly newsworthy because outbreaks are quite common and disease is typically mild. In children, Fifth Disease typically causes a rash on the face, trunk and limbs. The same type of rash can occur in adults, as can joint point or swelling. Severe complications can develop in pregnant women. There is no vaccine. Fifth Disease is caused by Parvovirus B19, a fact that sometimes leads to questions about dogs because of peoples' awareness about canine parvovirus.

Canine parvovirus is a highly infectious cause of life-threatening diarrhea in dogs, mainly puppies. Canine parvovirus vaccination is a very important component of routine vaccines for dogs.

Questions often arise about whether dogs can be a source of Fifth Disease, or whether people with this disease can infect dogs. The parvovirus that causes Fifth Disease is not the same virus that causes disease in dogs. Human parvovirus cannot infect dogs, nor vice versa.

An interesting fact about Fifth Disease is the origin of its name. The name originates from a standard list of causes of rash from the early 1900s. This condition was the fifth on the list, and for some reason, it became known as ‘Fifth Disease’. None of the other disease were named by their ranking.

About: Worms & Germs Blog is an educational website coordinated by Drs. Scott Weese and Maureen Anderson of the Ontario Veterinary College's Centre for Public Health and Zoonoses. The site was initial set up with the help of funding from City...More...

Worms and Germs BlogPublished by University of Guelph Centre for Public Health & Zoonoses
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The Centre for Public Health and Zoonoses offers information relating to zoonotic diseases (diseases transmitted from animals to people), including aspects of human and pet health, infection prevention and control, and vaccination. It is located at the University of Guelph, in Ontario, Canada